Photoelectric smoke detectors are known for monitoring a path or area and providing an indication of the presence of smoke or other particles in the monitored area. The detectors are usually of the spot type or beam type. The spot type of detector employs a photoelectric or ionization sensor in a housing, and detects smoke presence in the housing. In the beam type or long path type of detector, a light beam is projected along a path, and a sensor is located at the far end of the path, or at the sending end of the path with a retroreflector placed at the far end of the path to reflect light back to the sending end.